Use of fragments of oxytocin for the preparation of a pharmaceutical composition in order to create eustasis

ABSTRACT

The present invention relates to the use di-, tri- and tetrapeptide fragments of oxytocin or mesotocin for the preparation of a pharmaceutical composition in order to create eustasis. The invention also relates to di-, tri- and tetrapeptide fragments of oxytocin or mesotocin for medical use, as well as a pharmaceutical composition comprising at least one di-, tri- or tetrapeptide fragment of oxytocin or mesotocin in order to create eustasis.

[0001] The present invention relates to the use di-, tri- andtetrapeptide fragments of oxytocin or mesotocin for the preparation of apharmaceutical composition in order to create eustasis. The inventionalso relates to di-, tri- and tetrapeptide fragments of oxytocin ormesotocin for medical use, as well as a pharmaceutical compositioncomprising at least one di-, tri- or tetrapeptide fragment of oxytocinor mesotocin in order to create eustasis.

BACKGROUND OF THE INVENTION

[0002] Oxytocin was one of the first peptide hormones to be isolated andsequenced. It is a nonapeptide with two cysteine residues that form adisulfide bridge between positions 1 and 6 and corresponds to theformula

[0003] A similar nonapetide is mesotocin having the formula

[0004] For a long time the only effects attributed to oxytocin were itsstimulating effects on milk ejection and uterine contractions, but inthe past decades it has been shown that oxytocin exerts a wide spectrumof effects within the central nervous system, CNS. It has been suggestedthat oxytocin participates in the control of memory and learningprocesses and of various types of behaviour such as feeding, locomotion,as well as maternal and sexual behavior. Oxytocin is also suggested toparticipate in the control of cardiovascular functions,thermoregulation, and pain threshold and fluid balance. There is alsoevidence that oxytocin is involved in the control of variousimmunological processes. It has recently been demonstrated that oxytocininjections cause a lowering of blood pressure and increased weightgain—long lasting effects after repetitive administration. As a centralstimulating substance oxytocin plays an important role in theinteraction between mother and progeny in mammals. The products may alsobe used prophylactic in young human beings e.g. already in new bornbabies or young children to prevent the development of diseases later onin life which diseases are dependent on stress conditions during thefetal life. Such conditions may be heart/vessel diseases such as stroke,heart infarct, hypertension, and diabetes.

[0005] In the human body oxytocin is produced in the paraventricularnucleus, PVN, and the supraoptic nucleus, SON, of the hypothalamus. Itdiffers by only two amino acids from vasopressin, which is also producedin these nuclei. The magnocellular oxytocinergic neurones of the SON andPVN send oxons to the posterior pituitary from which oxytocin isreleased into the circulation. Parvocellular neurones that originate inthe PVN project into multiple areas within CNS. The oxytocin-producingcells are innervated by cholinergic, catecholaminergic as well aspeptidergic neurones. The presence of oxytocin in different tissuesoutside the brain, such as the uterus, ovaries, testis, thymus, adrenalmedulla and pancreas has been demonstrated and oxytocin is suggested toexert local effects in these organs.

[0006] A parallel secretion of oxytocin into the brain regions and intothe circulation occurs in response to some stimuli such as suckling, butother stimuli can cause separate activation of oxytocinergic neurones,terminating in the brain or the pituitary.

[0007] Mesotocin, which has been isolated from frogs, has similareffects as oxytocin.

[0008] The oxytocin and mesotocin molecule may be digested into smallerfragments. Of special interest are fragments containing 2-4 peptidesobtained by cleavage amino acids from the amino terminal and/or thecarboxyl terminal. As used in the context of the present invention, theterm “di-, tri- and tetrapeptide fragments of oxytocin or mesotocin”correspond to such fragments. Such fragments may either be amidated ornot at the C-terminal. It has now been shown that di-, tri- andtetrapeptide fragments of oxytocin or mesotocin may be used in order tocreate eustasis.

[0009] By the expression “eustasis” we understand a psychophysiologicalstate, i e a combination of a psychological and physiological state. Thepsychological state is characterised by calm and positive socialinteractions such as trust and breast-feeding. The physiological stateis characterised by muscle relaxation, lowered cardiovascular activityand enhanced gastrointestinal activity. Besides, pulse rate and bloodpressure are kept at a low, healthy and balanced level, and the vagallycontrolled gastrointestinal tract is activated, promoting digestion andstorage of nutrients.

[0010] Eustasis should not be confused with euphoria, which is more anintense feeling of joy and reward. Furthermore, the creation of eustasisshould not be confused with the treatment of depression or any otherdisease states. For example, the treatment of depression refers to aconversion from a disease state to a healthy state, whereas the creationof eustasis refers to a conversion from one healthy state to anotherhealthy state.

[0011] In the Examples, some compounds according to the invention areadministered to rats. A decrease in locomotor activity, blood pressureand hormone levels was noticed, suggested that the compounds have aeustasis creating effect.

[0012] U.S. Pat. No. 5,767,083 (D1) discloses the use of Pro-Leu-Gly-NH₂and Pro-Ile-Gly-NH₂. The first-mentioned oligopeptide is calledmelanocyte stimulating inhibitory factor, abbreviated MIF, and is usedagainst depression. Furthermore, D1 describes the combination of sucholigopeptides known antidepressants such as amitriptyline, fluoxetine,and sertraline. EP 146 113 (D2) discloses that Pro-Leu-Gly-NH₂ may beused against disease states caused by elevated melanotropine levels,such as high blood pressure. D2 also discloses the dipeptideLeu-Gly-NH₂.

[0013] Regulatory Peptides From Molecular Biology to Function, Advancesin Biochemical Psychopharmacology, Vol. 33, Ed. E. Costa and M.Trabucchi, Raven Press, New York (1982) (D3) discloses the effect ofLeu-Gly-NH₂, acetic acid salt in the treatment of neuropsychiatricillness.

[0014] No documents disclose tetrapeptide fragments of oxytocin andmesotocin. As mentioned above, some di- and tripeptide fragments ofoxytocin and mesotocin are previously known in the art. However, it isnot previously known to use di- and tripeptide fragments of oxytocin andmesotocin in order to create eustasis. Besides, no pharmaceuticalcompositions comprising the di- and tripeptides and oxytocin ormesotocin are known in the art.

SUMMARY OF THE INVENTION

[0015] The present invention relates to the use of di, tri- andtetrapeptide fragments of oxytocin or mesotocin for the preparation of apharmaceutical composition in order to create eustasis. The inventionalso relates to di-, tri- and tetrapeptide fragments of oxytocin ormesotocin, preferably for medical use. It also relates to as apharmaceutical composition comprising at least one di-, tri- ortetrapeptide fragment of oxytocin or mesotocin, and a pharmaceuticallyacceptable carrier and, optionally oxytocin or mesotocin. Such apharmaceutical composition may be used in order to create eustasis.

DETAILED DESCRIPTION OF THE INVENTION

[0016] One object of the present invention is the use of a compound ofthe formula (I): X₁-X₂-X₃-X₄ (SEQ ID NO: 3)

[0017] wherein X₁ is selected from Cys and nothing,

[0018] X₂ is selected from Pro and nothing;

[0019] X₃ is selected from Leu and Ile;

[0020] X₄ is selected from Gly and nothing;

[0021] provided that if X₁ is Cys, then X₂ is Pro;

[0022] provided that if X₄ is nothing, then X₁ is Cys and X₂ is Pro;

[0023] as well as amidated forms thereof;

[0024] for the preparation of a pharmaceutical composition, optionallycomprising oxytocin or mesotocin, in order to create eustasis.

[0025] By “nothing” is meant that the letters respectively may have nomeaning or may represent a bond and that there may be a direct bondbetween the items (letter, atom or group) situated to the right and tothe left, respectively, of the letter designating “nothing”. Forexample, in formula (I), when X₁ designates nothing, the resultingmolecule corresponds to X₂-X₃-Gly. When X₄ designates nothing, theresulting molecule corresponds to X₁-X₂-X₃.

[0026] By “amidated” form is meant that the carboxylic acid group of thecarboxyl terminal amino acid residue of the resulting peptide isamidated.

[0027] It is preferred that the compound of formula (I) is selectedfrom: Cys-Pro-Leu-Gly (SEQ ID NO: 4) Cys-Pro-Leu-Gly-NH₂, (SEQ ID NO: 5)Cys-Pro-Ile-Gly, (SEQ ID NO: 6) Cys-Pro-Ile-Gly-NH₂, (SEQ ID NO: 7)Pro-Leu-Gly, (SEQ ID NO: 8) Pro-Leu-Gly-NH₂, (SEQ ID NO: 9) Pro-Ile-Gly,(SEQ ID NO: 10) Pro-Ile-Gly-NH₂, (SEQ ID NO: 11) Cys-Pro-Leu, (SEQ IDNO: 12) Cys-Pro-Leu-NH₂ (SEQ ID NO: 13) Cys-Pro-Ile, (SEQ ID NO: 14)Cys-Pro-Ile-NH₂ (SEQ ID NO: 15) Leu-Gly, (SEQ ID NO: 16) Leu-Gly-NH₂,(SEQ ID NO: 17) Ile-Gly (SEQ ID NO: 18) and Ile-Gly-NH₂. (SEQ ID NO: 19)

[0028] It is also preferred that the compound is administered in anamount of 1 μg to 1 mg/kg body weight of the patient.

[0029] Another object of the present invention is a compound of theformula (I): X₁-X₂-X₃-X₄ (SEQ ID NO: 3)

[0030] wherein X₁ is selected from Cys and nothing,

[0031] X₂ is selected from Pro and nothing;

[0032] X₃ is selected from Leu and Ile;

[0033] X₄ is selected from Gly and nothing;

[0034] provided that if X₁ is Cys, then X₂ is Pro;

[0035] provided that if X₄ is nothing, then X₁ is Cys and X₂ is Pro;

[0036] as well as amidated forms thereof;

[0037] provided that if X₁ is nothing, X₂ is Pro, then X₄ is Gly innon-amidated form; and

[0038] provided that if X₁ and X₂ are nothing, and X₃ is Leu, then X₄ isGly in non-amidated form.

[0039] By “non-amidated” form is meant that the carboxylic acid group ofthe carboxyl terminal amino acid residue of the resulting peptide is notamidated.

[0040] It is preferred that the compound of formula (I) is selectedfrom: Cys-Pro-Leu-Gly (SEQ ID NO: 4) Cys-Pro-Leu-Gly-NH₂, (SEQ ID NO: 5)Cys-Pro-Ile-Gly, (SEQ ID NO: 6) Cys-Pro-Ile-Gly-NH₂, (SEQ ID NO: 7)Pro-Leu-Gly, (SEQ ID NO: 8) Pro-Ile-Gly, (SEQ ID NO: 10) Cys-Pro-Leu,(SEQ ID NO: 12) Cys-Pro-Leu-NH₂ (SEQ ID NO: 13) Cys-Pro-Ile, (SEQ ID NO:14) Cys-Pro-Ile-NH₂ (SEQ ID NO: 15) Leu-Gly, (SEQ ID NO: 16) Ile-Gly(SEQ ID NO: 18) and Ile-Gly-NH₂. (SEQ ID NO: 19)

[0041] Another object of the present invention is a compound as definedabove for medical use.

[0042] Another object of the present invention is a pharmaceuticalcomposition comprising at least one compound as defined above, and apharmaceutically acceptable carrier and, optionally, oxytocin ormesotocin, in order to create eustasis.

[0043] It is preferred that the effective concentration of the compoundin the pharmaceutical composition is 4-70% by weight, preferably 0.1-50%by weight.

[0044] The invention also relates to the peptides mentioned above inboth D- and L-form. Especially the invention relates to the L-form. Byinversion of the peptide sequence thereof, the D-form could be convertedto the L-form. The effect of the D- and L-forms are the same. These andthe peptides above can be produced by methods known to a person skilledin the art e.g. according to Merrifield, P. B., “Solid Phase Synthesis”,Angew. Chemie, 1985, No. 97, p. 801.

[0045] The pharmaceutical compositions are prepared in a manner known toa person skilled in the pharmaceutical art. The carrier or the excipientcould be a solid, semi-solid or liquid material that could serve as avehicle or medium for the active ingredient. Suitable carriers orexcipients are known in the art. The pharmaceutical composition could beadapted to oral, parenteral, intravaginal, or topical use and could beadministered to the patient as tablets, capsules, suppositories,solutions, suspensions or the like.

[0046] The pharmaceutical compositions could be administered orally,e.g. with an inert diluent or with an edible carrier. They could beenclosed in gelatine capsules or be compressed to tablets. For oraltherapeutic administration the compounds according to the inventioncould be incorporated with excipients and used as tablets, lozenges,capsules, elixirs, suspensions, syrups, wafers, chewing gums and thelike. These preparations should contain at least 4% by weight of thecompounds according to the invention, the active ingredient, but couldbe varied according to the special form and could, suitably, be 4-70% byweight of the unit. The amount of the active ingredient that iscontained in compositions is so high that a unit dosage form suitablefor administration is obtained.

[0047] The tablets, pills, capsules, lozenges and the like could alsocontain at least one of the following adjuvants: binders such asmicrocrystalline cellulose, gum tragacanth or gelatine, excipients suchas starch or lactose, disintegrating agents such as alginic acid,Primogel, corn starch, and the like, lubricants such as magnesiumstearate or Sterotex, glidants such as colloidal silica dioxide, andsweetening agents such as saccharose or saccharin could be added orflavourings such as peppermint, methyl salicylate or orange flavouring.When the unit dosage form is a capsule it could contain in addition tothe type above a liquid carrier such as polyethylene glycol or a fattyoil. Other unit dosage forms could contain other different materialsthat modify the physical form of the unit dosage form, e.g. as coatings.Accordingly, tablets or pills could be coated with sugar, shellac orother enteric coating agents. A syrup could in addition to the activeingredient contain saccharose as a sweetening agent and somepreservatives, dyes and flavouring agents. Materials that are used forpreparation of these different compositions should be pharmaceuticallypure and non-toxic in the amounts used.

[0048] For parental administration the compounds according to theinvention could be incorporated in a solution or suspension. Parenteraladministration refers to the administration not through the alimentarycanal but rather by injection through some other route, as subcutaneous,intramuscular, intraorbital, intracapsular, intraspinal, intrasternal,intravenous, intranasal, intrapulmonary, through the urinary tract,through eye drops, rectal or intravaginal (e.g. as a suppository, avagitorium, a cream or an ointment), through the lactiferous tract incattle, into an organ such as bone marrow, etc. Bone marrow may also betreated in vitro. These preparations could contain at least 0.1% byweight of an active compound according to the invention but could bevaried to be approximately 0.1-50% thereof by weight. The amount of theactive ingredient that is contained in such compositions is so high thata suitable dosage is obtained.

[0049] The solutions or suspensions could also comprise at least one ofthe following adjuvants: sterile diluents such as water for injection,saline, fixed oils, polyethylene glycols, glycerol, propylene glycol orother synthetic solvents, antibacterial agents such as benzyl alcohol ormethyl paraben, antioxidants such as ascorbic acid or sodium bisulfite,chelating agents such as ethylene diamine tetraacetic acid, buffers suchas acetates, citrates or phosphates, and agents for adjustment of thetonicity such as sodium chloride or dextrose. The parenteral preparationcould be enclosed in ampoules, disposable syringes or multiple dosagevessels made of glass or plastic.

[0050] For topical administration the compounds according to theinvention could be incorporated in a solution, suspension, or ointment.These preparations could contain at least 0.1% by weight of an activecompound according to the invention but could be varied to beapproximately 0.1-50% thereof by weight. The amount of the activeingredient that is contained in such compositions is so high that asuitable dosage is obtained. The administration could be facilitated byapplying touch, pressure, massage, heat, warms, or infrared light on theskin, which leads to enhanced skin permeability. Hirvonen, J., Kalia, YN, and Guy, R H. Transdermal delivery of peptides by iontophoresis, NatBotechnol 1996 December; 14(13): 1710-1713 describes how to enhance thetransport of a drug via the skin using the driving force of an appliedelectric field. Preferably, iontophoresis is effected at a slightlybasic pH.

[0051] Other administration forms are inhalation through the lungs,buccal administration via the mouth, enteral administration via thesmall intestine, and local administration with a release, preferably aslow release, of the active substance e g in the form of a ring. Allthese administration forms could be effected by means known by a personskilled in the art.

[0052] All publications mentioned herein are hereby incorporated byreference. By the expression “comprising” we understand including butnot limited to. Thus, other non-mentioned substances, additives orcarriers may be present.

[0053] The invention will be illuminated by the following Examples,which are only intended to illuminate and not restrict the invention inany way.

EXAMPLES Materials and Methods

[0054] Animals. Eight week-old male Sprague-Dawley rats (280-300 g) wereobtained from B&K Universal AB, Sollentuna, Sweden.

[0055] Experimental procedure. SEQ ID NO: 5 was dissolved inphysiological saline (1 mg/ml) and administered subcutaneously to sixrats at a dose of 1 mg/kg for five consecutive days. Six rats receivedphysiological saline only as a control. Two days after the lasttreatment, the rats were exposed to blood pressure determination withthe cuff technique. The locomotor behaviour was studied three days afterthe end of the treatment. The next day the animals were decapitated andblood was collected.

[0056] Statistics. The results are presented as means ±SD. Statisticalanalysis was performed by means of 2-way ANOVA followed by Bonferroni'stest for post hoc comparison. A Students t-test was performed. p-valuesof 0.05 or less were regarded as statistically significant.

Example 1 Locomotor Activity Observations

[0057] The spontaneous motor activity was observed in a squareopen-field arena (680×680×450 mm), equipped with two rows of photocells(8×8), sensitive to infrared light. Two identical frames of photocellswere placed at two levels, 40 and 125 mm above the floor, respectively.The open-field was enclosed in a ventilated, sound-attenuating box witha Perspex top. Measurements were made in the dark and performed between0.900-16.00 h.

[0058] The number of photocell beam interruptions were collected on anIBM-compatible PC computer allowing the registration of locomotoractivity (all interruptions of photobeams at the lower level) andrearing (all interruptions of photobeams at the upper level). The datawere subject to a square root transformation. For further details on theapparatus and the computer software used, including a schematic drawingof the equipment, see Ericson, E., Samuelsson, J., and Ahlenius, S.(1991). Photocell measurements of rat motor activity: A contribution tosensitivity and variation in behavioral observations. J Pharmacol Meth25, 111-122. Furthermore, the peripheral activity was measured. Byperipheral activity is meant that the animals are located in the cornersof the arena. When the animals are frightened, they have a highertendency to be located in the corners ie have a high peripheralactivity. On the contrary, when the animals are more calm, they have ahigher tendency to be located in the middle of the arena ie have a lowerperipheral activity.

[0059] Results

[0060] The locomotor activity was significantly decreased in ratstreated with SEQ ID NO: 5, as well as the amount of rearing. Likewise,the amount of peripheral activity decreased. Together, these data showthat the compounds according to the invention induce a calming effect.

Example 2 Plasma Hormone Determinations

[0061] Trunk blood was collected in ice-chilled tubes, containingheparin (10 IU/ml) (Pharmacia-Upjohn, Stockholm, Sweden) and aprotinin(500 IU/ml) (Trasylol, Bayer, Germany). The blood samples werecentrifuged and plasma was removed and frozen (−20° C.).

[0062] Oxytocin

[0063] Oxytocin was measured with a specific radioimmunoassay developedin this laboratory (Stock, S., and Uvnäs-Moberg, K. (1988). Increasedplasma levels of oxytocin in response to stimulation of the sciatic andvagal nerves and in response to touch and pinch in anaesthetized rats.Acta Physiol Scand 132, 29-34.). Plasma samples were purified withreversed-phase chromatography using C18 Waters SEP-PAK cartridges. Theantiserum anti-oxytocin (rabbit) for RIA, KA-19 (Euro Diagnostica,Malmö, Sweden) and the tracer [¹²⁵I]-Tyr²-oxytocin (Du Pont Nen ResearchProducts, Boston, Mass.) were used. The cross-reactivity of the antibodywas less than 0.01% with vasopressin, somatostatin LH-RH and ACTH. Thelimit of detection was 2 pmol/l. The intra- and interassay coefficientsof variation were 11 and 13%, respectively.

[0064] Gastrin

[0065] Gastrin was immunoassayed as described by Smedh, U., andUvnäs-Moberg, K. (1994) Intracerebroventricularly administeredcorticotropin-releasing factor releases somatostatin through acolinergic, vagal pathway in freely fed rats. Acta Physiol Scand 151,241-247. The gastrin standard (Pensinsula Laboratories), the antiserumNo 260 4 (gift fom J F Rehfeld, Rigshospitalet, Copenhagen Denmark) andthe tracer [¹²⁵I]-gastrin 8 Euro Diagnostic, Malmö Sweden were used. Thereactivity of the antibody had the same potency for gastrin-17 andgastrin-34. The limit of detection of the assay was 6 pmol/l. The intra-and interassay coefficients of variation were 10 and 13%, respectively.

[0066] Cholecystokinin (CCK)

[0067] CCK was immunoassayed as described by Smedh and Uvnäs Moberg,supra. Plasma samples were purified with reversed-phase chromatographyusing C18 Waters SEP PAK cartridges. The CCK standard (PeninsulaLaboratories) the antiserum OAL 656 (Otsuka Assay Laboratories, Japan)and the tracer [¹²⁵I]-CCK (Du Pont NEN Research Products Boston, Mass.)were used. The antiserum OAL 656 was raised against N-terminal aminoacid residue of sulphated CCK 8 and reacted with CCK 8, CCK 39 but notwith gastrin and its related peptides. The limit of detection of theassay was 3-6 pmol/l The intra- and interassay coefficients of variationwere 10 and 12% respectively.

[0068] Results

[0069] The animals treated for five consecutive days with SEQ ID NO: 5had the hormone levels as shown in Table 1. TABLE 1 Hormone levels ofrats treated with SEQ ID NO: 5 compared to control rats. Hormone levelsin hormone treated Hormone levels in Hormone rats (N = 6) control rats(N = 6) p-value Oxytocin 29.7 ± 7.2  53.6 ± 14.3 0.004 Gastrin  85 ±19.3  130 ± 52.6 0.09 CCK 8.4 ± 3.5 14.6 ± 7.6  0.06

[0070] These data indicate that the compounds according to the inventionsignificantly lower the oxytocin levels, whereby the cholinergic vagalmechanisms are influenced. This suggest a stimulating influence ondigestion and anabolic metabolism.

Example 3 Measurement of Blood Pressure and Heart Rate

[0071] Blood pressure and heart rate were measured on conscious animalsby placing a cuff (Kent RTBP-002, Somedic Sales, Farsta, Sweden) on thebase of the tail. The cuff was connected to a Grass 7P8 sphygmanometerand a Grass 7P8DC amplifier with a printer. The rats were habituated tothe entire test procedure for 2-3 weeks before the procedure started.

[0072] Results

[0073] The blood pressure was significantly decreased in rats treatedwith SEQ ID NO: 5. The systolic and diastolic blood pressures are givenin Table 2. TABLE 2 Hormone levels of rats treated with SEQ ID NO: 5compared to control rats. Value in hormone Value in control Bloodpressure treated rats (N = 6) rats (N = 6) p-value Systolic 116 ± 9.1 132.1 ± 9.2  0.01 Diastolic 87.3 ± 18.9 104.9 ± 14.8 0.01

[0074]

1 19 1 9 PRT Artificial Sequence Synthetic peptide 1 Cys Tyr Ile Gln AsnCys Pro Leu Gly 1 5 2 9 PRT Artificial Sequence Synthetic peptide 2 CysTyr Ile Gln Asn Cys Pro Ile Gly 1 5 3 4 PRT Artificial SequenceSynthetic peptide 3 Xaa Xaa Xaa Xaa 1 4 4 PRT Artificial SequenceSynthetic peptide 4 Cys Pro Leu Gly 1 5 4 PRT Artificial SequenceSynthetic peptide 5 Cys Pro Leu Gly 1 6 4 PRT Artificial SequenceSynthetic peptide 6 Cys Pro Ile Gly 1 7 4 PRT Artificial SequenceSynthetic peptide 7 Cys Pro Ile Gly 1 8 3 PRT Artificial SequenceSynthetic peptide 8 Pro Leu Gly 1 9 3 PRT Artificial Sequence Syntheticpeptide 9 Pro Leu Gly 1 10 3 PRT Artificial Sequence Synthetic peptide10 Pro Ile Gly 1 11 3 PRT Artificial Sequence Synthetic peptide 11 ProIle Gly 1 12 3 PRT Artificial Sequence Synthetic peptide 12 Cys Pro Leu1 13 3 PRT Artificial Sequence Synthetic peptide 13 Cys Pro Leu 1 14 3PRT Artificial Sequence Synthetic peptide 14 Cys Pro Ile 1 15 3 PRTArtificial Sequence Synthetic peptide 15 Cys Pro Ile 1 16 2 PRTArtificial Sequence Synthetic peptide 16 Leu Gly 1 17 2 PRT ArtificialSequence Synthetic peptide 17 Leu Gly 1 18 2 PRT Artificial SequenceSynthetic peptide 18 Ile Gly 1 19 2 PRT Artificial Sequence Syntheticpeptide 19 Ile Gly 1

1-8. (cancelled).
 9. A method of creating eustasis, comprisingadministering to a patient a pharmaceutical composition having theformula (I): (I) X₁-X₂-X₃-X₄, (SEQ ID NO: 3)

wherein X¹ is selected from Cys and nothing; X₂ is selected from Pro andnothing; X₃ is selected from Leu and Ile; X4 is selected from Gly andnothing; provided that when X₁ is Cys, X₂ is Pro; provided that when X₄is nothing, X₁ is Cys and X₂ is Pro; and amidated forms thereof.
 10. Amethod according to claim 9, wherein said composition further comprisesat least one of oxytocin or mesotocin.
 11. A method according to claim9, wherein said composition is selected from the group consisting of:Cys-Pro-Leu-Gly (SEQ ID NO: 4) CYS-PRO-LEU-GLY-NH₂, (SEQ ID NO: 5)Cys-Pro-Ile-Gly, (SEQ ID NO: 6) Cys-Pro-Ile-Gly-NH₂, (SEQ ID NO: 7)Pro-Leu-Gly, (SEQ ID NO: 8) Pro-Leu-Gly-NH₂, (SEQ ID NO: 9) Pro-Ile-Gly,(SEQ ID NO: 10) Pro-Ile-Gly-NH₂, (SEQ ID NO: 11) Cys-Pro-Leu, (SEQ IDNO: 12) Cys-Pro-Leu-NH₂ (SEQ ID NO: 13) Cys-Pro-Ile, (SEQ ID NO: 14)Cys-Pro-Ile-NH₂ (SEQ ID NO: 15) Leu-Gly, (SEQ ID NO: 16) Leu-Gly-NH₂,(SEQ ID NO: 17) Ile-Gly, (SEQ ID NO: 18) and Ile-Gly-NH₂. (SEQ ID NO:19)


12. A method according to claim 10, wherein said composition is selectedfrom the group consisting of: Cys-Pro-Leu-Gly (SEQ ID NO: 4)Cys-Pro-Leu-Gly-NH₂, (SEQ ID NO: 5) Cys-Pro-Ile-Gly, (SEQ ID NO: 6)Cys-Pro-Ile-Gly-NH₂, (SEQ ID NO: 7) Pro-Leu-Gly, (SEQ ID NO: 8)Pro-Leu-Gly-NH₂, (SEQ ID NO: 9) Pro-Ile-Gly, (SEQ ID NO: 10)Pro-Ile-Gly-NH₂, (SEQ ID NO: 11) Cys-Pro-Leu, (SEQ ID NO: 12)Cys-Pro-Leu-NH₂ (SEQ ID NO: 13) Cys-Pro-Ile, (SEQ ID NO: 14)Cys-Pro-Ile-NH₂ (SEQ ID NO: 15) Leu-Gly, (SEQ ID NO: 16) Leu-Gly-NH₂,(SEQ ID NO: 17) Ile-Gly, (SEQ ID NO: 18) and Ile-Gly-NH₂. (SEQ ID NO:19)


13. A method according to claim 9, wherein said composition isadministered to said patient in an amount from 1 μg to 1 mg per kgpatient body weight.
 14. A method according to claim 10, wherein saidcomposition is administered to said patient in an amount from 1 μg to 1mg per kg patient body weight.
 15. A method according to claim 11,wherein said composition is administered to said patient in an amountfrom 1 μg to 1 mg per kg patient body weight.
 16. A method according toclaim 12, wherein said composition is administered to said patient in anamount from 1 μg to 1 mg per kg patient body weight.
 17. A compoundhaving the formula (I): (I) X₁-X₂-X₃-X₄, (SEQ ID NO: 3)

wherein X₁ is selected from Cys and nothing, and amidated forms thereof;X₂ is selected from Pro and nothing, and amidated forms thereof; X₃ isselected from Leu and Ile, and amidated forms thereof; X4 is selectedfrom Gly and nothing, and amidated forms thereof; provided that if X₁ isCys, X₂ is Pro, and amidated forms thereof; provided that if X₄ isnothing, X₁ is Cys and X₂ is Pro, and amidated forms thereof; providedthat if X₁ is nothing and X₂ is Pro, then X₄ is Gly in non-amidatedform; and provided that if X₁ is nothing, X₂ is nothing, and X₃ is Leu,then X₄ is Gly in non-amidated form.
 18. A compound according to claim17, wherein the compound is selected from the group consisting of:Cys-Pro-Leu-Gly (SEQ ID NO: 4) Cys-Pro-Leu-Gly-NH₂, (SEQ ID NO: 5)Cys-Pro-Ile-Gly, (SEQ ID NO: 6) Cys-Pro-Ile-Gly-NH₂, (SEQ ID NO: 7)Pro-Leu-Gly, (SEQ ID NO: 8) Pro-Ile-Gly, (SEQ ID NO: 10) Cys-Pro-Leu,(SEQ ID NO: 12) Cys-Pro-Leu-NH₂ (SEQ ID NO: 13) Cys-Pro-Ile, (SEQ ID NO:14) Cys-Pro-Ile-NH₂ (SEQ ID NO: 15) Leu-Gly, (SEQ ID NO: 16) Ile-Gly(SEQ ID NO: 18) and Ile-Gly-NH₂. (SEQ ID NO: 19)


19. A method of effecting a medical treatment, comprising administeringa compound according to claim 17 to a patient.
 20. A method of effectinga medical treatment, comprising administering a compound according toclaim 18 to a patient.
 21. A pharmaceutical composition comprising: atleast one compound according to claim 17; and a pharmaceuticallyacceptable carrier, wherein the composition creates eustasis in apatient.
 22. A pharmaceutical composition according to claim 21, furthercomprising at least one of oxytocin and mesotocin.
 23. A pharmaceuticalcomposition comprising: at least one compound according to claim 18; anda pharmaceutically acceptable carrier, wherein the composition createseustasis in a patient.
 24. A pharmaceutical composition according toclaim 23, further comprising at least one of oxytocin and mesotocin 25.A pharmaceutical composition according to claim 21, wherein theeffective concentration of the compound is 4-70% by weight.
 26. Apharmaceutical composition according to claim 21, wherein the effectiveconcentration of the compound is 0.1-50% by weight.
 27. A pharmaceuticalcomposition according to claim 23, wherein the effective concentrationof the compound is 4-70% by weight.
 28. A pharmaceutical compositionaccording to claim 23, wherein the effective concentration of thecompound is 0.1-50% by weight.